Had to sign up for this. Take extra care to use appropriate materials for a house this age or you'll create more problems than you solve. Solid stone walls need to breathe!
Make sure you've spoken with a surveyor specialising in heritage property too.
PIR boards are almost certainly unsuitable.
https://www.victorian-house.co.uk/ (be sure to pick up a copy of the Haynes Victorian House manual, it's a gem)
https://www.lime.org.uk/community/boards-insulation.html
I'm currently having to undo poor choices of modernisation on a building of the same age, which caused tremendous problems with damp.